Memory array and non-volatile memory device of the same

ABSTRACT

A non-volatile memory device is provided. The non-volatile memory device includes a substrate area, two storage units, a spacer structure and two control units. The storage units include two anti-fuse gates each having a gate dielectric layer between the anti-fuse gate and the substrate area and two diffusion areas. The spacer structure is formed on the substrate area and between the two anti-fuse gates and contacts thereto. Each of the diffusion areas is a first doping area doped with a first type dopant contacting one of the two anti-fuse gates. Each of the control units includes a select gate formed on the substrate area and a second doping area. A first side of the select gate contacts one of the diffusion areas of the storage unit. The second doping area is doped with the first type dopant and contacts a second side of the select gate.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number 102133192, filed Sep. 13, 2013, which is herein incorporated by reference.

BACKGROUND

Field of Invention

The present invention relates to a semiconductor technology. More particularly, the present invention relates to a memory array and a non-volatile memory device of the same.

Description of Related Art

The development of semiconductor memory devices having higher integration and lower power consumption has been the focus of recent research.

Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory, flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy disk drives, and magnetic tape), optical disc drives, and early computer storage methods such as paper tape and punch cards.

Since the trend of the design of the electronic devices is to shrink the size thereof, it is a great challenge to keep the size of electronic components smaller without affecting the operations and the functions of the electronic devices. The present non-volatile memory fabrication technologies are not able to efficiently shrink the size of the devices even if additional fabrication processes or number of masks are used.

Accordingly, what is needed is a reliable design of the non-volatile memory devices to address the issues mentioned above.

SUMMARY

The invention provides a non-volatile memory device. The non-volatile memory device includes a substrate area, two storage units, a spacer structure and two control units. The two storage units include two anti-fuse gates and two diffusion areas. The two anti-fuse gates are formed on the substrate area and each has a gate dielectric layer between the anti-fuse gates and the substrate area. Each of the two diffusion areas is a first doping area doped with a first type dopant, wherein the two diffusion areas are formed in the substrate area and are located at two sides of the two anti-fuse gates such that the two diffusion areas contact the two anti-fuse gates respectively. The spacer structure is formed on the substrate area and is formed between the two anti-fuse gates and contacting thereto. Each of the two control units includes a select gate and a second doping area. The select gate is formed on the substrate area and includes a dielectric layer between the select gate and the substrate area, wherein a first side of the select gate contacts one of the two diffusion areas of the storage unit. The second doping area is formed in the substrate area, doped with the first type dopant and contacting a second side of the select gate.

Another aspect of the present invention is to provide a memory array. The memory array includes a plurality of non-volatile memory devices, a plurality of control lines, a plurality of first access lines and a plurality of second access lines. Each of the non-volatile memory devices includes a substrate area, two storage units, a spacer structure and two control units. The two storage units include two anti-fuse gates and two diffusion areas. The two anti-fuse gates are formed on the substrate area and each has a gate dielectric layer between the anti-fuse gates and the substrate area. Each of the two diffusion areas is a first doping area doped with a first type dopant, wherein the two diffusion areas are formed in the substrate area and are located at two sides of the two anti-fuse gates such that the two diffusion areas contact the two anti-fuse gates respectively. The spacer structure is formed on the substrate area and is formed between the two anti-fuse gates and contacting thereto. Each of the two control units includes a select gate and a second doping area. The select gate is formed on the substrate area and includes a dielectric layer between the select gate and the substrate area, wherein a first side of the select gate contacts one of the two diffusion areas of the storage unit. The second doping area is formed in the substrate area, doped with the first type dopant and contacting a second side of the select gate. Each of the control lines is electrically connected to one of the two anti-fuse gates of the two storage units of at least one of the non-volatile memory devices. Each of the first access lines is electrically connected to the select gate of one of the two control units of at least one of the non-volatile memory devices. Each of the second access lines is electrically connected to the second doping area of one of the two control units of at least one of the non-volatile memory devices.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims.

It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:

FIG. 1 is a diagram of a memory array in an embodiment of the present invention;

FIG. 2 is a diagram of the layout of the non-volatile memory device in an embodiment of the present invention;

FIG. 3 is a cross-sectional view of the non-volatile memory device in an embodiment of the present invention;

FIG. 4 is a cross-sectional view of the non-volatile memory device in another embodiment of the present invention;

FIG. 5 is a cross-sectional view of the non-volatile memory device in another embodiment of the present invention;

FIG. 6A is a is a diagram illustrating the reading current generated when different source line voltages are applied to the neighboring n-th and n+1-th storage units under the condition that the n-th storage unit has already been programmed in an embodiment of the present invention;

FIG. 6B is a is a diagram illustrating the reading current generated when different source line voltages are applied to the neighboring n-th and n+1-th storage units under the condition that the n-th storage unit has not been programmed in an embodiment of the present invention;

FIG. 7 is a diagram illustrating the currents of the non-volatile memory device during the on-state and during the off-state under the condition of performing the write and read operations on the non-volatile memory device for a long time in an embodiment of the present invention; and

FIG. 8 is a diagram illustrating the current of the non-volatile memory device under the condition of performing high temperature baking thereon for a long time in an embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

FIG. 1 is a diagram of a memory array 1 in an embodiment of the present invention. The memory array 1 includes a plurality of non-volatile memory devices 10, a plurality of control lines SLn, SLn+1, . . . , SLn+3, a plurality of first access lines WLn, WLn+1, . . . , WLn+3 and a plurality of second access lines BLm, BLm+1, . . . , BLm+3.

In an embodiment, the memory array 1 is formed by the non-volatile memory devices 10 arranged in a two dimensional array. Each of the first access lines WLn, WLn+1, . . . , WLn+3 is a word line and each of the second access lines BLm, BLm+1, . . . , BLm+3 is a bit line to select at least one of the non-volatile memory devices 10. Each of the control lines SLn, SLn+1, . . . , SLn+3 is a source line. When one of the selected non-volatile memory devices 10 is selected, the non-volatile memory device 10 can be written or read according to the voltage applied by the control lines SLn, SLn+1, . . . , SLn+3.

FIG. 2 is a diagram of the layout of the non-volatile memory device 10 in an embodiment of the present invention. FIG. 3 is a cross-sectional view of the non-volatile memory device 10 in an embodiment of the present invention. The non-volatile memory device 10 includes a substrate area 20, two storage units 22 a and 22 b, two control units 24 a and 24 b and a spacer structure 26.

In the present embodiment, the substrate area 20 is a P-well area. The two storage units 22 a and 22 b include two anti-fuse gates 220 a and 220 b and two diffusion areas 222 a and 222 b.

The two anti-fuse gates 220 a and 220 b are formed on the substrate area 20 and have gate dielectric layers 224 a and 224 b, wherein the gate dielectric layer 224 a is formed between the anti-fuse gate 220 a and the substrate area 20, and the gate dielectric layer 224 b is formed between the anti-fuse gate 220 b and the substrate area 20. The anti-fuse gate 220 a, the diffusion area 222 a and the gate dielectric layer 224 a form a data storage unit. The anti-fuse gate 220 b, the diffusion area 222 b and the gate dielectric layer 224 b form another data storage unit.

In the present embodiment, the gate dielectric layers 224 a and 224 b can be oxide layers, nitride layers or layers formed by high-k material. Moreover, in the present embodiment, each of the anti-fuse gates 220 a and 220 b includes a gate. The gate can be a poly-Si gate or a metal gate.

Each of the two diffusion areas 222 a and 222 b is a first doping area doped with a first type dopant, wherein the two diffusion areas are formed in the substrate area 20. In the present embodiment, each of the two diffusion areas 222 a and 222 b is an N-type doping area (n+). Explained in a different way, each of the two diffusion areas 222 a and 222 b is formed by doping the dopant such as P or As in the substrate area 20. The diffusion area 222 a is located at one side of the anti-fuse gate 220 a and contacts thereto. The diffusion area 222 b is located at one side of the anti-fuse gate 220 b and contacts thereto.

The spacer structure 26 is formed on the substrate area 20 and is formed between the two anti-fuse gates 220 a and 220 b and contacting thereto. The spacer structure 26 isolates the anti-fuse gates 220 a and 220 b to prevent the anti-fuse gates 220 a and 220 b from affecting each other.

In an embodiment, the spacer structure 26 can be a single structure such that the spacer structure 26 is directly formed to cover the substrate area 20. The spacer structure 26 can also include two independent structures formed close to each other or contacting to each other. The presence of the spacer structure 26 allows the two anti-fuse gates 220 a and 220 b to be formed geometrically close to each other while the two anti-fuse gates 220 a and 220 b are still electrically isolated to each other. The storage units 22 a and 22 b can be shrink to a smaller size due to the presence of the spacer structure 26.

The control unit 24 a includes a select gate 240 a and a second doping area 242 a. The control unit 24 b includes a select gate 240 b and a second doping area 242 b. The select gates 240 a and 240 b are formed on the substrate area 20 and include a dielectric layer 244 a and a dielectric layer 244 b respectively. The dielectric layer 244 a is formed between the select gate 240 a and the substrate area 20. The dielectric layer 244 b is formed between the select gate 240 b and the substrate area 20. In the present embodiment, the dielectric layers 244 a and 244 b can be oxide layers, nitride layers or layers formed by high-k material.

A first side of the select gate 240 a contacts the diffusion area 222 a of the storage unit 22 a. A first side of the select gate 240 b contacts the diffusion area 222 b of the storage unit 22 b. The doping area 242 a is formed by doping the substrate area 20 with the first type dopant, which is the N-type dopant in the present embodiment. Moreover, the doping area 242 a contacts a second side of the select gate 240 a. The doping area 242 b is formed by doping the substrate area 20 with the first type dopant as well, which is the N-type dopant in the present embodiment. Moreover, the doping area 242 b contacts a second side of the select gate 240 b. As a result, the select gate 240 a, the doping area 242 a and the diffusion area 222 a that contacts the select gate 240 a together form a metal-oxide semiconductor device. The select gate 240 b, doping area 242 b and the diffusion area 222 b that contacts the select gate 240 b together form another metal-oxide semiconductor device.

The control lines SLn and SLn+1 are electrically connected to the anti-fuse gates 220 a and 220 b respectively. The first access lines WLn and WLn+1 (i.e. the word lines) are electrically connected to the select gates 240 a and 240 b respectively. The second access lines BLm (i.e. the bit line) is electrically connected to the doping areas 242 a and 242 b at the same time.

As a result, an anti-fuse storage structure is formed in the non-volatile memory device 10 between the diffusion area 222 a and the anti-fuse gate 220 a. Another anti-fuse storage structure is formed in the non-volatile memory device 10 between the diffusion area 222 b and the anti-fuse gate 220 b. Table 1 shown below illustrates the operation conditions when different voltages are applied to the storage unit (e.g. the storage units 22 a and 22 b) fabricated by the 28 nanometer process, in which these different voltages include the voltages applied by the word line, the source line, the bit line and voltage applied to the P-well.

TABLE 1 (Unit: volts) Word line Source line Bit line P-well Write Selected 1.2 4 0 0 Unselected 0 0 floating 0 Read Selected 0.85 1.5 0 0 Unselected 0 0 floating 0

Taking the storage unit 22 a as an example, when the gate dielectric layer 224 a is under a normal condition, there is no or only a few amount of current flowing therethrough under the read operation. The gate dielectric layer 224 a is at an open-circuited status that represents a low state (0) in an embodiment. When the voltage of the word line (WL) is 1.2 volts and the voltage of the bit line (BL) is 0 volt, the non-volatile memory device 10 corresponding to the word line and the bit line is selected. Further, the write operation is performed according to the 4 volts voltage applied by the source line (SL) to the anti-fuse gate 220 a to make the gate dielectric layer 224 a breakdown. The gate dielectric layer 224 a is at a short-circuited status that represents a high state (1) in an embodiment since there is a larger amount of current flowing therethrough. Therefore, such a structure in the non-volatile memory device 10 is called the anti-fuse storage structure.

As a result, the write and the read operations of the non-volatile memory device 10 in the present invention can be performed by the process described above to accomplish a data storage mechanism. The spacer structure 26 acts as a mask during the doping process for forming the diffusion areas 222 a and 222 b such that the area between the storage units 22 a and 22 b is not doped. During the write operation performed on the storage unit 22 a, the spacer structure 26 prevents the neighboring storage unit 22 b from damage when the high voltage for the write operation is applied to the storage unit 22 a. Moreover, the presence of the spacer structure 26 allows the two anti-fuse gates 220 a and 220 b to be formed geometrically close to each other while the two anti-fuse gates 220 a and 220 b are still electrically isolated to each other. The storage units 22 a and 22 b can be shrink to a smaller size due to the presence of the spacer structure 26, and a smaller total area of the memory array 1 can be accomplished.

FIG. 4 is a cross-sectional view of the non-volatile memory device 10 in another embodiment of the present invention. The non-volatile memory device 10 includes the substrate area 20, the two storage units 22 a and 22 b and the two control units 24 a and 24 b that are identical to these components illustrated in FIG. 3. The following description only focuses on the differences between the embodiments illustrated in FIG. 4 and FIG. 3. The identical components are not described herein.

In the present embodiment, the non-volatile memory device 10 includes two spacer structures 40 a and 40 b. The spacer structures 40 a and 40 b are formed on the substrate area 20 and contact to the anti-fuse gates 220 a and 220 b respectively. The two spacer structures 40 a and 40 b are apart from each other with a distance D. In an embodiment, the two spacer structures 40 a and 40 b can still provide the isolation mechanism even when the distance D therebetween is smaller than 100 nanometers such that the area between the storage units 22 a and 22 b is not doped during the doping process for forming the diffusion areas 222 a and 222 b.

FIG. 5 is a cross-sectional view of the non-volatile memory device 10 in another embodiment of the present invention. The non-volatile memory device 10 includes the substrate area 20, the two storage units 22 a and 22 b and the two control units 24 a and 24 b that are identical to these components illustrated in FIG. 3. The following description only focuses on the differences between the embodiments illustrated in FIG. 5 and FIG. 3. The identical components are not described herein.

In the present embodiment, the non-volatile memory device 10 includes two spacer structures 50 a and 50 b and an isolation area 52. The isolation area 52 is a doping area doped by a second type dopant. In the present embodiment, the isolation area 52 is a P-type doping area (p+). Explained in a different way, the isolation area 52 is formed by doping the dopant such as B in the substrate area 20. The isolation area 52 provides the isolation mechanism when the distance between the two spacer structures 50 a and 50 b are larger to isolate the storage units 22 a and 22 b such that the storage units 22 a and 22 b do not affect each other.

FIG. 6A is a is a diagram illustrating the reading current generated when different source line voltages are applied to the neighboring n-th and n+1-th storage units under the condition that the n-th storage unit has already been programmed (corresponding to the storage of a high level bit) in an embodiment of the present invention.

FIG. 6B is a is a diagram illustrating the reading current generated when different source line voltages are applied to the neighboring n-th and n+1-th storage units under the condition that the n-th storage unit has not been programmed (corresponding to the storage of a low level bit) in an embodiment of the present invention.

FIG. 7 is a diagram illustrating the currents of the non-volatile memory device 10 during the on-state (corresponding to the storage of the high level bit) and during the off-state (corresponding to the storage of the low level bit) under the condition of performing the write and read operations on the non-volatile memory device 10 for a long time in an embodiment of the present invention.

FIG. 8 is a diagram illustrating the current of the non-volatile memory device 10 under the condition of performing high temperature baking (e.g. 450 hours; 150° C.) thereon for a long time in an embodiment of the present invention.

From the above diagrams, it is known that the memory array and the non-volatile memory device of the same can accomplish the data storage mechanism by using the anti-fuse structure. Moreover, the presence of the spacer structure can provide a good isolation between the storage units. There is no current degradation under the condition of repetitive read and write operations and under the condition of high temperature baking for a long time. Not only the isolation between the storage units is reliable, the stability of the memory array and the non-volatile memory device is also high.

Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims. 

What is claimed is:
 1. A non-volatile memory device comprising: a substrate area; two storage units comprising: two anti-fuse gates formed on the substrate area and each having a gate dielectric layer between the anti-fuse gates and the substrate area; and two diffusion areas each being a first doping area doped with a first type dopant, wherein the two diffusion areas are formed in the substrate area and are located at two sides of the two anti-fuse gates such that the two diffusion areas contact the two gate dielectric layer respectively; a spacer structure formed on the substrate area and between the two anti-fuse gates and contacting thereto; and two control units each comprising: a select gate formed on the substrate area comprising a dielectric layer between the select gate and the substrate area, wherein a first side of the select gate contacts one of the two diffusion areas of the storage unit; and a second doping area formed in the substrate area, doped with the first type dopant and contacting a second side of the select gate.
 2. The non-volatile memory device of claim 1, wherein each of the two anti-fuse gates is electrically connected to a control line, the select gate of each of the two control units is electrically connected to a first access line respectively and the second doping area of the two control units is electrically connected to a second access line.
 3. The non-volatile memory device of claim 2, wherein the first access line is a word line and the second access line is a bit line.
 4. The non-volatile memory device of claim 1, wherein each of the two anti-fuse gates and the select gate is a poly-Si gate or a metal gate.
 5. The non-volatile memory device of claim 1, wherein the select gate and the second doping area of one of the two control units and the corresponding one of the two diffusion areas together form a metal-oxide semiconductor device.
 6. The non-volatile memory device of claim 1, wherein the gate dielectric layer of one of the two anti-fuse gates is under a breakdown condition such that the corresponding one of the two diffusion areas is under a first data storing status.
 7. The non-volatile memory device of claim 1, wherein the gate dielectric layer of one of the two anti-fuse gates is not under a breakdown condition such that the corresponding one of the two diffusion areas is under a second data storing status.
 8. A memory array comprising: a plurality of non-volatile memory devices each comprising: a substrate area; two storage units comprising: two anti-fuse gates formed on the substrate area and each having a gate dielectric layer between the anti-fuse gates and the substrate area; and two diffusion areas each being a first doping area doped with a first type dopant, wherein the two diffusion areas are formed in the substrate area and are located at two sides of the two anti-fuse gates such that the two diffusion areas contact the two gate dielectric layer respectively; a spacer structure formed on the substrate area and between the two anti-fuse gates and contacting thereto; and two control units each comprising: a select gate formed on the substrate area and comprising a dielectric layer between the select gate and the substrate area, wherein a first side of the select gate contacts one of the two diffusion areas of the storage unit; and a second doping area formed in the substrate area, doped with the first type dopant and contacting a second side of the select gate; a plurality of control lines each electrically connected to one of the two anti-fuse gates of the two storage units of at least one of the plurality of non-volatile memory devices; a plurality of first access lines each electrically connected to the select gate of one of the two control units of at least one of the plurality of non-volatile memory devices; and a plurality of second access lines each electrically connected to the second doping area of one of the two control units of at least one of the plurality of non-volatile memory devices.
 9. The memory array of claim 8, wherein each of the first access lines is a word line and each of the second access lines is a bit line. 